INVESTIGATION OF C1Q REGULATION OF MONOCYTE DEVELOPMENT

Abstract

C1q is an abundant plasma complement protein which is produced by myeloid cells. However, local synthesis of C1q is important as C1q is involved in many functions. Thus, we hypothesized that osteoclasts may be a potential source of C1q. Indeed, both cultured and endogenous osteoclasts produced C1q. Production of C1q can be regulated by different stimulants and showed remarkable increase by IFNg. Furthermore, immobilized C1q increased expression of osteoclast markers and suggests a potential role of C1q in osteoclastogenesis. Previous studies have shown that C1q modulates monocyte development and mediates morphological changes. To understand how C1q regulates monocyte development, we investigated and showed that immobilized C1q affects the morphology and adhesion of different cell types. Intact C1q is required to mediate such effects. Known C1q receptors are not involved in the process. Lastly, commercial anti-C1q antibodies enhanced the effects of immobilized C1q but this was not observed with patient samples.